Bristles for use in a toothbrush have conventionally been manufactured from a filament that is prepared from a thermoplastic polymer. There is a continuing need to improve the cleaning efficacy of toothbrush bristles manufactured from such polymeric filaments. This invention relates to a method of improving the cleaning efficacy of such a toothbrush bristle by reducing the coefficient of friction that the bristle experiences when in contact with a tooth. It has been found that a useful means of reducing the coefficient of friction experienced by a toothbrush bristle when in contact with a tooth is to manufacture the bristle from a filament prepared from a composition containing a thermoplastic polymer and a slip agent.
U.S. Pat. No. 5,462,798 (“Gueret”) discloses a brush used as an applicator for thick liquid cosmetic products such as nail varnish or mascara. The bristles or hairs of the brush are made from a plastic that contains a slip agent. The presence of the slip agent reduces the wettability of the hairs of the applicator, and limits the attachment of the product to the hairs. This condition enhances the tendency of the product to remain on the substrate to which applied, rather than on the hair, and facilitates distribution of a thicker layer of the product on the substrate.
There is no mention in Gueret of the use of such a hair or bristle for cleaning teeth. We have found, however, that the use of a bristle manufactured from a filament prepared from a composition of a thermoplastic polymer and a slip agent does reduce the coefficient of friction experienced by the bristle when in contact with a tooth to such an extent that the cleaning efficacy of the bristle is improved.